Logs being taken to a pulp and paper factory in Riau province, Sumatra. Photo: Dita Alangkara/AP

The destruction of Sumatra's natural forests is accelerating global climate change and pushing endangered species closer to extinction, a new report warned today.

A study from WWF claims that converting the forests and peat swamps of just one Sumatran province into plantations for pulpwood and palm oil is generating more annual greenhouse gas emissions than the Netherlands, and is endangering local elephant and tiger populations.

The fastest rate of deforestation in Indonesia is occurring in central Sumatra's Riau province, where some 4.2m hectares (65%) of its tropical forests and peat swamps have been cleared for industrial plantations in the past 25 years, the study shows.

Since 1982, about 30% of the province's natural forest has been cleared for palm oil plantations, 24% for industrial pulpwood plantations, and 17% has become so-called wasteland – land that has been deforested but not replaced by any crop cover. Twenty-five years ago, according to the report, forest covered 78% of the Riau province. Today it covers just 27%. In just one year, 2005-06, it lost 286,146 hectares – 11% of forest cover.

Illegal and legal forest clearance for the development of settlements, infrastructure and agriculture has traditionally driven deforestation in Riau, but the "speed and finality" of forest conversion for the rapidly expanding pulp and paper and palm oil industries is matched "by no other type of deforestation", the report says.

Satellite image of smoke from forest fires and land clearance in Riau. Photo: EPA
The resulting average annual CO2 from forest loss, degradation, peat decomposition and fires between 1990-2007 in Riau province alone was 0.22 gigatons – higher than that of the Netherlands, or equivalent to 58% of Australia's total annual emissions, or 39% of the UK's annual emissions, the report says.

The report, a joint effort between WWF, Remote Sensing Solutions and Hokkaido university in Japan, claims to be the first piece of research to analyse the connection between deforestation and forest degradation, global climate change and declining wildlife populations.

It has analysed deforestation and forest degradation over a 25-year period between 1982-2007. By using satellite images to map land cover and usage it has identified the main drivers of forest clearance. Researchers used remote sensing analysis and two different land management scenarios to estimate historical and future CO2 emissions related to deforestation up to 2015.

Riau is home to vast peatlands that are estimated to hold south-east Asia's largest store of carbon, and contains some of the most biodiverse ecosystems that are home to critically endangered species such as Sumatra elephants and tigers, rhinos and orang-utans.

In the past 25 years, WWF says there has been a clear correlation in Riau between the clearance of forests and declining wildlife populations, largely thought to be due to an increase in human-wildlife conflict as animals are driven from their disappearing forest habitats.

Elephant numbers may have declined as much as 84% in Riau. Photo: Wayne Lawler/Corbis
The report shows there has been a huge decline in elephant numbers – from an estimated 1,067-1,617 in 1984 to possibly as few as 210 individuals today. If this trend continues and the two largest remaining elephant forests are not protected, Riau's wild elephant population will face extinction, the report warns.

Similarly, figures in the report show that Riau's Sumatran tiger population has declined by 70% in 25 years, from 640 to 192 today. Unless the last remaining patches of tiger habitat are connected by wildlife corridors, these too will face extinction, the report says.

"We found that Sumatra's elephants and tigers are disappearing even faster than their forests are in Riau," said WWF International's species programme director, Dr Susan Lieberman. "This is happening because as wildlife search for new habitat and food sources, they increasingly come into conflict with people and are killed.

"The fragmentation and opening up of new forest areas also increases both the access and the opportunities for poaching. Therefore, a concerted effort to save these forests will contribute significantly to slowing the rate of global climate change, and will give tigers, elephants, and local communities a real chance for a future inSumatra."

About 20% of the world's greenhouse gas emissions are estimated to come from global annual deforestation, which often takes place in the most biodiverse regions of the world, such as Brazil and Indonesia.

Indonesia's carbon emissions are likely to increase, the study predicts, as most future forest clearance will be conducted in areas with deep peat, which releases greenhouse gases when it decomposes or burns.

During December's UN climate change conference in Bali, the Indonesian minister for forestry promised to provide incentives to stop unsustainable forestry practices, and to protect Indonesia's forests. The governor of Riau province has also made a public commitment to protect the province's remaining forest. WWF is urging the government to uphold these promises.

"If the commitments by the Indonesian government are implemented, it will not only save its endangered species, but actually slow the rate of global climate change through the carbon savings," said Ian Kosasih, the director of WWF Indonesia's forest programme.

"If government and local industry were to create positive incentives for projects to reduce emissions by saving forests in Riau province, it would both protect the province's massive carbon stores and also contribute to the economies of local communities that are dependent on these forests," Kosasih added.

The demand for palm oil, which is fuelling much of the forest clearance, has risen in recent years to meet a global demand for biofuels.

Last week, the transport secretary, Ruth Kelly, ordered a government review of the environmental and economic damage caused by growing biofuels.

Ministers say a number of studies have emerged recently that question the environmental benefits of biofuels, and the government wants to check that UK and European biofuel targets will not cause more problems than they solve.